refactor: migrate pg:info to cli/core

[k80bowman]

Work item

Notes

• Please take a close look at the logic, especially the displayDB function. I had to do a bit of refactoring on that one because of Typescript requirements.

Testing

• Check out this branch and run yarn and yarn build
• Find or set up an app with a postgres database
• Run ./bin/run pg:info --help and verify that you get the expected result
• Run ./bin/run pg:info -a APP_NAME DATABASE_NAME. Verify that you get the expected result.

[justinwilaby]

Just one comment for an optional consideration but otherwise, LGTM!